This project is a development board for the Atmel ATmega16, ATmega32, ATmega164p, ATmega324p, ATmega644p, ATmega1284p, and ATmega8535. The board itself comes from either ExpressPCB or from Futurlec, and the parts from Digikey, Mouser, or Newark. I have always had my prototype PC boards made by ExpressPCB, because there are no unknowns with them. With the software below, the board can make an "ATmega32 Arduino" or an "ATmega644 Arduino". [Download Dev40a design files] It includes:
The 40-pin AVR development board has a form factor that is the same as the ExpressPCB Miniboard. You can also get them from Futurlec for a really good price, if you're in the area. From here in the USA the shipping times are pretty long, but the price can be better if you order a different quantity than the 3 boards you get from ExpressPCB. For instance, you pay about the same price for 10 boards without solder mask from Futurlec as you do for three boards with solder mask from ExpressPCB. The difference is what makes the express in ExpressPCB. It can take 6 weeks to get your boards from Futurlec (in the USA).
You could probably single side the design, or double side without feedthroughs, and follow the standard pcb fabrication steps outlined here and make your own pc board for this project. There is also information on pcb toner transfer methods.
There are no surface mount parts, so you don't need to get boards with solder mask, unless you want the nomenclature.
You can add a prototype board on top to prototype your circuits, using the same type of connectors used by the Arduino shields.
Here is the Arduino environment for this board with either an ATmega32 or an ATmega644p. It works as of version 18. I haven't tried it on newer versions yet. I hope to try it soon with an ATmega324p and an ATmega164p. Unzip it into the hardware directory. It will create a folder named "dev40a". That folder contains the hardware files and bootloaders to make this board compatible with Arduino. I can't take credit for most of the code, since I picked it up in various places. The code lists it's source, but the bootloader hex files are a modified version of the bootloader modified by LadyAda and a dozen others.
These schematic diagrams are for the Dev40A 40-pin AVR ATmega Developement Board. The board supports Atmel ATmega16, ATmega32, ATmega134, ATmega324, ATmega644, ATmega1284, and ATmega8535 MCU's.
The power supply runs on 7VDC to 12VDC, and supplies regulated 5VDC for all circuits. It outputs up to 1 AMP, should you provide that much to it, and you don't mind putting a heatsink on the regulator. I use a 12VDC 500mA switching wall wart for everything I do, and it has proved to be more than adequate so far. I would recomend a 7V 900mA switching power supply for higher currents. You can't go lower in voltage without getting below the regulator's dropout voltage, and you can't go higher because the power drop across the regulator will exceed the cooling capability of this heatsink-less design.
The I/O section includes four switches and four LEDs, in addition to two potentiometers. All the I/O is ready to hook directly to the ATmega pins. The switches were tough to decide upon. They are two-pin versions of the four-pin square switches everyone likes to use. Unfortunately, they come in about 20 different tactile force versions. Some you can barely push and some that just touching will trigger.